Define array index as NonMaxU32

Based on the definition in spec, [array index][] is only valid from zero
to u32::MAX - 1. It would be helpful to use the NonMaxU32 type to define
it as the property key instead so that contributors won't forget to
check the validity.

[array index]: https://tc39.es/ecma262/#array-index

boa_engine/src/object/internal_methods/arguments.rs

@@ -44,7 +44,7 @@ pub(crate) fn arguments_exotic_get_own_property(
             .borrow()
             .as_mapped_arguments()
             .expect("arguments exotic method must only be callable from arguments objects")
-            .get(*index as usize)
+            .get(index.get() as usize)
         {
             // a. Set desc.[[Value]] to Get(map, P).
             return Ok(Some(
@@ -81,8 +81,8 @@ pub(crate) fn arguments_exotic_define_own_property(
         obj.borrow()
             .as_mapped_arguments()
             .expect("arguments exotic method must only be callable from arguments objects")
-            .get(index as usize)
-            .map(|value| (index as usize, value))
+            .get(index.get() as usize)
+            .map(|value| (index.get() as usize, value))
     } else {
         None
     };
@@ -173,7 +173,7 @@ pub(crate) fn arguments_exotic_get(
             .borrow()
             .as_mapped_arguments()
             .expect("arguments exotic method must only be callable from arguments objects")
-            .get(*index as usize)
+            .get(index.get() as usize)
         {
             // a. Assert: map contains a formal parameter mapping for P.
             // b. Return Get(map, P).
@@ -212,7 +212,7 @@ pub(crate) fn arguments_exotic_set(
             obj.borrow_mut()
                 .as_mapped_arguments_mut()
                 .expect("arguments exotic method must only be callable from arguments objects")
-                .set(index as usize, &value);
+                .set(index.get() as usize, &value);
         }
     }
 
@@ -243,7 +243,7 @@ pub(crate) fn arguments_exotic_delete(
             obj.borrow_mut()
                 .as_mapped_arguments_mut()
                 .expect("arguments exotic method must only be callable from arguments objects")
-                .delete(*index as usize);
+                .delete(index.get() as usize);
         }
     }
 

boa_engine/src/object/internal_methods/array.rs

@@ -38,7 +38,9 @@ pub(crate) fn array_exotic_define_own_property(
             array_set_length(obj, desc, context)
         }
         // 3. Else if P is an array index, then
-        PropertyKey::Index(index) if index < u32::MAX => {
+        PropertyKey::Index(index) => {
+            let index = index.get();
+
             // a. Let oldLenDesc be OrdinaryGetOwnProperty(A, "length").
             let old_len_desc = super::ordinary_get_own_property(obj, &"length".into(), context)?
                 .expect("the property descriptor must exist");
@@ -201,14 +203,16 @@ fn array_set_length(
             .borrow()
             .properties
             .index_property_keys()
-            .filter(|idx| new_len <= **idx && **idx < u32::MAX)
+            .filter(|idx| new_len <= idx.get())
             .copied()
             .collect();
         keys.sort_unstable_by(|x, y| y.cmp(x));
         keys
     };
 
     for index in ordered_keys {
+        let index = index.get();
+
         // a. Let deleteSucceeded be ! A.[[Delete]](P).
         // b. If deleteSucceeded is false, then
         if !obj.__delete__(&index.into(), context)? {

boa_engine/src/object/internal_methods/integer_indexed.rs

@@ -1,5 +1,6 @@
 use crate::{
     builtins::{array_buffer::SharedMemoryOrder, typed_array::integer_indexed_object::ContentType},
+    nonmaxu32::NonMaxU32,
     object::JsObject,
     property::{PropertyDescriptor, PropertyKey},
     Context, JsResult, JsValue,
@@ -44,14 +45,16 @@ pub(crate) fn integer_indexed_exotic_get_own_property(
         // i. Let value be ! IntegerIndexedElementGet(O, numericIndex).
         // ii. If value is undefined, return undefined.
         // iii. Return the PropertyDescriptor { [[Value]]: value, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: true }.
-        Ok(integer_indexed_element_get(obj, *index as usize).map(|v| {
-            PropertyDescriptor::builder()
-                .value(v)
-                .writable(true)
-                .enumerable(true)
-                .configurable(true)
-                .build()
-        }))
+        Ok(
+            integer_indexed_element_get(obj, index.get() as usize).map(|v| {
+                PropertyDescriptor::builder()
+                    .value(v)
+                    .writable(true)
+                    .enumerable(true)
+                    .configurable(true)
+                    .build()
+            }),
+        )
     } else {
         // 2. Return OrdinaryGetOwnProperty(O, P).
         super::ordinary_get_own_property(obj, key, context)
@@ -74,7 +77,7 @@ pub(crate) fn integer_indexed_exotic_has_property(
     // a. Let numericIndex be ! CanonicalNumericIndexString(P).
     if let PropertyKey::Index(index) = key {
         // b. If numericIndex is not undefined, return ! IsValidIntegerIndex(O, numericIndex).
-        Ok(is_valid_integer_index(obj, *index as usize))
+        Ok(is_valid_integer_index(obj, index.get() as usize))
     } else {
         // 2. Return ? OrdinaryHasProperty(O, P).
         super::ordinary_has_property(obj, key, context)
@@ -103,7 +106,7 @@ pub(crate) fn integer_indexed_exotic_define_own_property(
         // iii. If Desc has an [[Enumerable]] field and if Desc.[[Enumerable]] is false, return false.
         // v. If Desc has a [[Writable]] field and if Desc.[[Writable]] is false, return false.
         // iv. If ! IsAccessorDescriptor(Desc) is true, return false.
-        if !is_valid_integer_index(obj, index as usize)
+        if !is_valid_integer_index(obj, index.get() as usize)
             || !desc
                 .configurable()
                 .or_else(|| desc.enumerable())
@@ -116,7 +119,7 @@ pub(crate) fn integer_indexed_exotic_define_own_property(
 
         // vi. If Desc has a [[Value]] field, perform ? IntegerIndexedElementSet(O, numericIndex, Desc.[[Value]]).
         if let Some(value) = desc.value() {
-            integer_indexed_element_set(obj, index as usize, value, context)?;
+            integer_indexed_element_set(obj, index.get() as usize, value, context)?;
         }
 
         // vii. Return true.
@@ -145,7 +148,7 @@ pub(crate) fn integer_indexed_exotic_get(
     // b. If numericIndex is not undefined, then
     if let PropertyKey::Index(index) = key {
         // i. Return ! IntegerIndexedElementGet(O, numericIndex).
-        Ok(integer_indexed_element_get(obj, *index as usize).unwrap_or_default())
+        Ok(integer_indexed_element_get(obj, index.get() as usize).unwrap_or_default())
     } else {
         // 2. Return ? OrdinaryGet(O, P, Receiver).
         super::ordinary_get(obj, key, receiver, context)
@@ -171,7 +174,7 @@ pub(crate) fn integer_indexed_exotic_set(
     // b. If numericIndex is not undefined, then
     if let PropertyKey::Index(index) = key {
         // i. Perform ? IntegerIndexedElementSet(O, numericIndex, V).
-        integer_indexed_element_set(obj, index as usize, &value, context)?;
+        integer_indexed_element_set(obj, index.get() as usize, &value, context)?;
 
         // ii. Return true.
         Ok(true)
@@ -198,7 +201,7 @@ pub(crate) fn integer_indexed_exotic_delete(
     // b. If numericIndex is not undefined, then
     if let PropertyKey::Index(index) = key {
         // i. If ! IsValidIntegerIndex(O, numericIndex) is false, return true; else return false.
-        Ok(!is_valid_integer_index(obj, *index as usize))
+        Ok(!is_valid_integer_index(obj, index.get() as usize))
     } else {
         // 2. Return ? OrdinaryDelete(O, P).
         super::ordinary_delete(obj, key, context)
@@ -231,7 +234,7 @@ pub(crate) fn integer_indexed_exotic_own_property_keys(
         // i. Add ! ToString(𝔽(i)) as the last element of keys.
         (0..inner.array_length())
             .into_iter()
-            .map(|index| PropertyKey::Index(index as u32))
+            .map(|index| PropertyKey::Index(NonMaxU32::new(index as u32).unwrap()))
             .collect()
     };
 

boa_engine/src/object/internal_methods/mod.rs

@@ -737,7 +737,7 @@ pub(crate) fn ordinary_own_property_keys(
 
     // 2. For each own property key P of O such that P is an array index, in ascending numeric index order, do
     // a. Add P as the last element of keys.
-    keys.extend(ordered_indexes.into_iter().map(Into::into));
+    keys.extend(ordered_indexes.into_iter().map(|idx| idx.get().into()));
 
     // 3. For each own property key P of O such that Type(P) is String and P is not an array index, in ascending chronological order of property creation, do
     // a. Add P as the last element of keys.

boa_engine/src/object/internal_methods/string.rs

@@ -113,10 +113,10 @@ pub(crate) fn string_exotic_own_property_keys(
         .properties
         .index_property_keys()
         .copied()
-        .filter(|idx| (*idx as usize) >= len)
+        .filter(|idx| (idx.get() as usize) >= len)
         .collect();
     remaining_indices.sort_unstable();
-    keys.extend(remaining_indices.into_iter().map(Into::into));
+    keys.extend(remaining_indices.into_iter().map(|idx| idx.get().into()));
 
     // 7. For each own property key P of O such that Type(P) is String and P is not
     // an array index, in ascending chronological order of property creation, do
@@ -159,7 +159,7 @@ fn string_get_own_property(obj: &JsObject, key: &PropertyKey) -> Option<Property
     // 6. If IsIntegralNumber(index) is false, return undefined.
     // 7. If index is -0𝔽, return undefined.
     let pos = match key {
-        PropertyKey::Index(index) => *index as usize,
+        PropertyKey::Index(index) => index.get() as usize,
         _ => return None,
     };
 

boa_engine/src/object/property_map.rs

@@ -1,5 +1,5 @@
 use super::{PropertyDescriptor, PropertyKey};
-use crate::{JsString, JsSymbol};
+use crate::{nonmaxu32::NonMaxU32, JsString, JsSymbol};
 use boa_gc::{custom_trace, Finalize, Trace};
 use indexmap::IndexMap;
 use rustc_hash::{FxHashMap, FxHasher};
@@ -30,7 +30,7 @@ unsafe impl<K: Trace> Trace for OrderedHashMap<K> {
 
 #[derive(Default, Debug, Trace, Finalize)]
 pub struct PropertyMap {
-    indexed_properties: FxHashMap<u32, PropertyDescriptor>,
+    indexed_properties: FxHashMap<NonMaxU32, PropertyDescriptor>,
     /// Properties
     string_properties: OrderedHashMap<JsString>,
     /// Symbol Properties
@@ -126,15 +126,15 @@ impl PropertyMap {
         SymbolPropertyValues(self.symbol_properties.0.values())
     }
 
-    /// An iterator visiting all indexed key-value pairs in arbitrary order. The iterator element type is `(&'a u32, &'a Property)`.
+    /// An iterator visiting all indexed key-value pairs in arbitrary order. The iterator element type is `(&'a NonMaxU32, &'a Property)`.
     ///
     /// This iterator does not recurse down the prototype chain.
     #[inline]
     pub fn index_properties(&self) -> IndexProperties<'_> {
         IndexProperties(self.indexed_properties.iter())
     }
 
-    /// An iterator visiting all index keys in arbitrary order. The iterator element type is `&'a u32`.
+    /// An iterator visiting all index keys in arbitrary order. The iterator element type is `&'a NonMaxU32`.
     ///
     /// This iterator does not recurse down the prototype chain.
     #[inline]
@@ -197,7 +197,7 @@ impl PropertyMap {
 /// An iterator over the property entries of an `Object`
 #[derive(Debug, Clone)]
 pub struct Iter<'a> {
-    indexed_properties: hash_map::Iter<'a, u32, PropertyDescriptor>,
+    indexed_properties: hash_map::Iter<'a, NonMaxU32, PropertyDescriptor>,
     string_properties: indexmap::map::Iter<'a, JsString, PropertyDescriptor>,
     symbol_properties: indexmap::map::Iter<'a, JsSymbol, PropertyDescriptor>,
 }
@@ -206,7 +206,7 @@ impl<'a> Iterator for Iter<'a> {
     type Item = (PropertyKey, &'a PropertyDescriptor);
     fn next(&mut self) -> Option<Self::Item> {
         if let Some((key, value)) = self.indexed_properties.next() {
-            Some(((*key).into(), value))
+            Some((key.get().into(), value))
         } else if let Some((key, value)) = self.string_properties.next() {
             Some((key.clone().into(), value))
         } else {
@@ -350,10 +350,10 @@ impl FusedIterator for SymbolPropertyValues<'_> {}
 
 /// An iterator over the indexed property entries of an `Object`
 #[derive(Debug, Clone)]
-pub struct IndexProperties<'a>(hash_map::Iter<'a, u32, PropertyDescriptor>);
+pub struct IndexProperties<'a>(hash_map::Iter<'a, NonMaxU32, PropertyDescriptor>);
 
 impl<'a> Iterator for IndexProperties<'a> {
-    type Item = (&'a u32, &'a PropertyDescriptor);
+    type Item = (&'a NonMaxU32, &'a PropertyDescriptor);
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
@@ -375,12 +375,12 @@ impl ExactSizeIterator for IndexProperties<'_> {
 
 impl FusedIterator for IndexProperties<'_> {}
 
-/// An iterator over the index keys (`u32`) of an `Object`.
+/// An iterator over the index keys (`NonMaxU32`) of an `Object`.
 #[derive(Debug, Clone)]
-pub struct IndexPropertyKeys<'a>(hash_map::Keys<'a, u32, PropertyDescriptor>);
+pub struct IndexPropertyKeys<'a>(hash_map::Keys<'a, NonMaxU32, PropertyDescriptor>);
 
 impl<'a> Iterator for IndexPropertyKeys<'a> {
-    type Item = &'a u32;
+    type Item = &'a NonMaxU32;
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
@@ -404,7 +404,7 @@ impl FusedIterator for IndexPropertyKeys<'_> {}
 
 /// An iterator over the index values (`Property`) of an `Object`.
 #[derive(Debug, Clone)]
-pub struct IndexPropertyValues<'a>(hash_map::Values<'a, u32, PropertyDescriptor>);
+pub struct IndexPropertyValues<'a>(hash_map::Values<'a, NonMaxU32, PropertyDescriptor>);
 
 impl<'a> Iterator for IndexPropertyValues<'a> {
     type Item = &'a PropertyDescriptor;